Harbour porpoise

Latin Phocoena phocoena
Manx Perkyn chadjin
Physical description

Harbour porpoise are small, stocky cetaceans with an adult length of 1.5 metres. They have a distinctive small, triangular dorsal fin located in the centre of the back and a small round head with no beak. They are dark grey in colour.

Behaviour Harbour porpoise (Phocoena phocoena) - dive sequenceHarbour porpoise are typically recognisable by their slow gentle surfacing behaviour, similar to a tyre rolling through the water just breaking the surface. Often the only visible body parts are the top of the back and the tiny triangular dorsal fin. Unlike dolphins, porpoises rarely display acrobatic behaviour such as breaching and bow riding. They are in fact notoriously timid and dislike boat activity, often diving away from on-coming vessels.

Group Size in Manx waters

Typically 1-4 individuals, often observed in pairs. Occasionally, bigger aggregations are seen, sometimes numbering more than 10 individuals if a good food source is available in a particular area.

Abundance and distribution
Harbour porpoise inhabit coastal waters of the Northern Hemisphere.
Manx waters

Harbour porpoise are the most common species of cetacean in Manx waters and are observed here year round. Although seen offshore, they tend to prefer shallower coastal waters where small shoaling fish are plentiful. The hotspot on the island is Port St Mary Ledges where they are often observed very close inshore feeding amongst the shallow ledges of rock. They are present along all areas of Manx coastline and the chances are, that if you stood by the coast on a very calm day, almost anywhere on the island, you have a good chance of spotting some.


Harbour porpoise are excellent predators with a wide and varied diet. Food can include many species of fish, squid, shellfish and octopus. Herring, mackerel and sand-eels make up a large part of their diet in Manx waters.